E-cadherin reactivity in invasive "lobular" carcinoma (case 4). A: Invasive carcinoma with pleomorphic lobular features showing predominantly alveolar and solid growth patterns and intermediate-high nuclear grade (Hematoxylin and eosin, left). Strong cell membrane E-cadherin reactivity in tumor cells and in normal adjacent ductal epithelium (Immunoperoxidase for E-cadherin, right). B: Some tumor cells demonstrate a punctate staining pattern within the cell membrane or in the cytoplasm (Immunoperoxidase for E-cadherin). C: Metastatic carcinoma with lobular characteristics involving an ipsilateral axillary lymph node (Hematoxylin and eosin, left). Tumor cells showing strong cell membrane reactivity for E-cadherin (Immunoperoxidase for E-cadherin, right).